2-[[[3-methyl-4-(2,2,2-trifluoroethoxy)-2-pyridinyl]methyl]sulfinyl]-1H-benzimidazole or a salt thereof having an antiulcer action is reported in Japanese Patent Application Laid-Open No. 50978/1986 (JP-61-50978A) and so on.
WO 94/27988 (Japanese Patent Application Laid-Open No. 509499/1995 (JP-7-509499A)) discloses, as optically pure compounds, sodium, magnesium, lithium, potassium and calcium salts of (+)-methoxy-2-[[(4-methoxy-3,5-dimethyl-2-pyridinyl)methyl]sulfinyl]-1H-benzimidazole (omeprazole) which are optically pure.
WO 99/38513 discloses a method of treating ulcers, etc. which comprises administering an optically pure (R)-lansoprazole or a pharmaceutically acceptable salt thereof. However, this literature practically fails to disclose how to produce the salt.
WO 92/8716 discloses a pyridylmethylsulfiniyl-1H-benzimidazol compound which is enantiomerically pure, or a salt thereof and a process for producing the same.
WO96/2535 (U.S. Pat. No. 5,948,789, Japanese Patent Application Laid-Open No. 504290/1998 (JP-10-504290A)) discloses a production process which comprises subjecting a thio compound to an oxidation reaction for forming an optically active sulfoxide compound such as omeprazole and, if desired, converting the sulfoxide compound into a salt thereof by a conventional process.
The pyridylmethylsulfinyl-1H-benzimidazole compounds (e.g., omeprazole, lansoprazole) described in these literatures are relatively inferior in stability. Moreover, it is difficult to provide an optically active lansoprazole with high purity. However, these literatures fail to disclose a process for improving a stability and a purity of an optically active lansoprazole.
It is, therefore, an object of the present invention to provide an optically active lansoprazole having a high stability and its application (e.g., a pharmaceutical composition such as an antiulcer agent).
Another object of the present invention is to provide an optically active lansoprazole having a high-purity and its application.
Still another object of the present invention is to provide an optically active lansoprazole which has an improved stability and is excellent in solubility and absorbability and its application.